Assemblies of weakly interacting molecules (so-called molecular aggregates) have become remarkably versatile quantum systems with applications in photography, opto-electronics, solar cells, and photo-biology. The remarkable properties of these aggregates stem from the strong transition dipole-dipole interaction between the individual molecules which leads to entangled eigenstates with excitation shared coherently by a large number of molecules. As a consequence, electronic excitation can migrate through the aggregate and new superradiant optical properties emerge.
In this talk, I will give an introduction on the relationship between the structure of the aggregate (spatial arrangement, molecular properties, and environment) and the resulting optical and transfer properties with a focus on the important role of coupling to vibrational modes. As examples, I will discuss molecules on dielectric surfaces and biological light harvesting systems. Finally, I will indicate the possibility to use machine learning techniques to extract information about structure and quantum dynamics from spectroscopic data and to use such techniques to design aggregates with specific desirable properties.
Alexander Eisfeld is independent group leader at the Max Planck Institute for the Physics of Complex Systems (MPIPKS). He has held this position since 2012, after spending a year at Harvard University (Aspuru-Guzik group) funded by a DFG research fellowship.
Eisfeld received his Ph.D. in physics in 2006 from the University of Freiburg, Germany (group of Prof. J.S. Briggs). His main research interests are collective effects and quantum-transport in atomic, molecular and nano-scale many-body systems. Examples are photosynthetic light-harvesting systems, aggregates of organic dyes, assemblies of ultra-cold Rydberg atoms or photonic systems. To handle these typically large and complex systems he uses a variety of approaches, which include molecular dynamics simulations, quantum chemistry methods, non-adiabatic quantum dynamics and open quantum system formalisms. One particular research interest is solving non-Markovian open quantum system dynamics using efficient stochastic Schrödinger equations. He uses these methods to interpret various types of spectroscopic data (including for example multidimensional femtosecond spectroscopy), to predict novel effects. One goal is then to find practical applications of the investigated systems.
For more information and opportunities to meet with the speaker, please contact Yuping Huang at [email protected]